How to get to the N – a call for interdisciplinary research on organic N utilization pathways by plants

Abstract Background and aims While nitrogen (N) derived from soil organic matter significantly sustains agricultural plants, the complexities of organic N utilization pathways remain poorly understood. Knowledge gaps persist regarding diverse organic N pools, the microbial processes in N mineralization, and how plants shape the N-mineralizing microbial community through root exudation. Results To address these gaps, we propose an integrated conceptual framework that explores the intricate interplay of soil, plant, and microbiome dynamics within the context of soil carbon (C) cycling. Emphasizing plant effects on gross depolymerization and deamination of organic N—a crucial yet often overlooked aspect—we aim to enhance our understanding of plant N utilization pathways. In this context, we suggest considering the linkages between root and hyphal exudation, followed by rhizosphere priming effects which in turn control N mobilization. Based on the relation between exudation and N turnover, we identify microbial necromass as a potentially important organic N source for plants. Furthermore, we propose applying root economic theory to gain insights into the diverse strategies employed by plants in accessing soil organic N. Stable isotope tracers and functional microbiome analytics provide tools to decipher the complex network of the pathways of organic N utilization. Conclusions The envisioned holistic framework for organic N utilization pathways, intricately connects plants, soil, and microorganisms. This lays the groundwork for sustainable agricultural practices, potentially reducing N losses.